We report on epitaxial growth of InP nanowires (NWs) from Cu seed particles by metal-organic vapor phase epitaxy (MOVPE). Vertically-aligned straight nanowires can be achieved in a limited temperature range between 340 ℃ and 370 ℃ as reported earlier. In this paper we present the effect of the Ⅴ/Ⅲ ratio on nanowire morphology, growth rate, and particle configuration at a growth temperature of 350 ℃. Two regimes can be observed in the investigated range of molar fractions. At high Ⅴ/Ⅲ ratios nanowires grow from a solid Cu₂In particle. At low Ⅴ/Ⅲ ratios, nanowire growth from two particle types occurs simultaneously: Growth from solid Cu₂In particles, and significantly faster growth from In-rich particles. We discuss a possible growth mechanism relying on a dynamic interplay between vapor–liquid–solid (VLS) and vapor–solid–solid (VSS) growth. Our results bring us one step closer to the replacement of Au as seed particle material as well as towards a deeper understanding of particle-assisted nanowire growth.